No, I know what you're getting at- a little lever like on a Hipshot D-Tuner that will raise/lower the action on all the strings, right?

The only problem I see in that is that a good setup is through a combination of truss rod and saddle adjustments. I think that if you were to raise/lower the saddles without adjusting the neck relief, you might not get the results that you're looking for.

Well, let's see, here's what I was thinking. You wouldn't need "much" of a change in height, maybe a few millimeters at most. You'd start out by intonating it at the lowest action. Then when you raise it, the neck relief will still be fine ('cause you're raising, not lowering), and the intonation shouldn't change "much" (even though it might change "a little", but for temporary purposes it should be okay). I was thinking not only mid-gig, but even mid-song. The Hipshot-lever concept should allow for a very rapid adjustment, and you'd just need a clever locking mechanism to keep the lever in place. Am I oversimplifying this equation, or is there a chance this could work?

Exactly. High action seems to have a different sound to it. There's kind of a compromise between sound and playability in many cases. If the action's very low, you get fantastic playability, but the notes start sounding thin and the strings generate some very bizarre frequencies when they're slapped. If the action's very high you get a lot of consistency and a nice fat sound, but the playability suffers. So I'm saying to myself, "self, why can't I have the best of both worlds, and be able to switch between them as needed"? It's not a really big or important thing, it's mainly that this type of thing should be possible in today's world of advanced technology. Sometimes that thin sound is desirable, and sometimes one has material that requires fast slapping. Most of the time, a nice fat sound is most useful. It would be great if I could get both of those in a single instrument without having to do a setup every time before changing things around.